1. A Brand-new Neutrino Detector “SciBar” (1) Status and prospects Masaya Hasegawa (Kyoto Univ.) for the K2K SciBar Group for the K2K SciBar Group Hakuba 10 th Symposium Feb. 15-18, 2004

2. K2K NDs status & Motivation for SciBar SciBar Detector Installation in last summer SciBar working status SummaryContents Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004

3. B.G. from non-QE 0 1 2 3 4 5 K2K current status Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Important ! K2K Oscillation analysis Oscillation max. E ~ 0.6GeV Null Oscillation probability < 1% Δm 2 = 1.5 ~ 3.9 ×10 -3 eV @ sin 2 2θ=1(90%CL) Need to study low energy νinteractions (Charged current Quasi-elastic, single π production) to maximize the sensitivity Flux (<1.0GeV) : ~10% BG @ Super-K : ~20% But !

4. What’s Needed ? Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 How to identify the CCQE Identify μ and P (No π ±/0 ) Observe all particle from ν interaction. (Full Active & Tracking) Identify the recoil Proton (from low momentum) PID (p/π) Large Volume

5. Motivation for SciBar Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 K2K Near Neutrino Detector 1kt water cherencov detector (25t fiducial) - detect both CCqe and nonQE as 1ring μevent (fraction ~ 50%) Scintillating fiber tracker (6t fiducial) - Low efficiency @ low energy - dead space around vertex (fraction ~60%) Need a new detector !

6. SciBar Detector Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Extruded scintillator (15t) Multi-anode PMT (64 ch.) Wave-length shifting fiber EM calorimeter 1.7m 3m Extruded scintillator with WLS fiber readout Neutrino target is scintillator itself 2.5 x 1.3 x 300 cm 3 cell ~15000 channels Detect from less than 10cm track Distinguish proton from pion by using dE/dx (fairly) large volume  High 2-track CC-QE efficiency  Identify ν interaction mode clearly Just constructed in last summer!

7. SciBar Component Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 64 charge info. 2 timing info. VME board Extruded Scintillator (1.3×2.5×300cm 3 ) ・ made by FNAL (same as MINOS) Wave length shifting fiber (1.5mmΦ) ・ Long attenuation length (~350cm)  Light Yield : 16.5p.e./cm/MIP Multi-Anode PMT ・ 2×2mm 2 pixel (3% cross talk @1.5mmΦ) ・ Gain Uniformity (20% RMS) ・ Good linearity (~200p.e. @6×10 5 ) Readout electronics  Takubo’s talk Top View

8. Expected Performance Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 PID (p/π) Momentum reconstruction Using dE/dx Info. Result from Beamtest 2001 (only using 10cm dE/dx info) p/π missID probability : ~ 1% ( @ 0.8GeV/c) @ P_eff=95% Momentum (for proton) : less than 10% ( below 1.0GeV/c) High Efficiency in finding/identifying low energy CCQE events

9. SciBar Installation Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 S.Aoki, J.Arygyriades, S.S.Choi, M.Hasegawa, Hiraide, K.Hayashi, A.K.Ichikawa, Iinuma, Eric J., E.J.Jeon, K.K.Joo, D.Kerr, K.Kobayasi, A.Kohara, J.Kubota, M.J.Lee, I.T.Lim, H.Maesaka, O.Mineev, T.Morita, Y.Nakanishi, K.Nishikawa, K.Nitta, P.Rovegno, T.Nakaya, T.Sasaki, A.Suzuki, K.K.Shiraishi, Y.Takubo, R.Terri, M.Tuchscher, S.Yamamoto, M.Yokoyama, M.Yoshida, Z.Nawang (and more?) Almost no change from this schedule! ( 体育会系的がんばり！）

10. SciBar Installation (1) Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004

11. SciBar Installation (2) Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004

12. SciBar Installation – complete ! Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004

13. SciBar in the News Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Nikkei News 2004.01.12 KEK News 2003.10.16 KEK News 2003.10.16

14. SciBar started νdata taking from Oct.10 and working well. - few dead channel (6/14336 = 0.04%) - collect ~7000 νint./10ton/5E18POT(1month) - collect calibration data (cosmic,LED) with beam We have already done - checking the basic hardware performance - calibration (energy,timing),detector alignment - comparing with MC and other detectors using Muon sample (very preliminary) Current Status Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 beampedestalLEDCosmic ray 0.6s 35  s 100ns, 1take 1  s,1take Suppression mode

15. SciBar Shot ! Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 p  CCQE candidate 3track event

16. SciBar Shot ! Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 NC pi0 candidate vertex (ν + N  ν + N + π 0)

17. SciBar Shot ! Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Nu_e event candidate Large energy deposit in Electron Catcher ν e Flux measurement  Estimation of Beam BG for ν e search at Super-K Short Baseline Oscillation  ν e appearance for LSND Region (Δm 2 : 1 ~ 10)

18. SciBar Shot ! Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 NC elastic scattering Nucleon spin crisis What carries the proton spin? - valence quarks,sea quarks or gluons? σ( ＮＣＥ )/σ(CCQE) ratio probes Strange sea contribution to nucleon spin (Nuclear Physics B 105 (2002) 62) (ν + N  ν + N)

19. Cosmic Ray Data Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 We use penetrating cosmic-ray muon as a (strip to strip) relative energy calibration source. Mean ~ 140 count (design value) response is very stable Top view Side view   Typical ADC distribution This fluctuation come from PMT Gain variation ADC count

20. Gain Monitor (1) Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 High Accuracy gain monitoring SystEm (HASE moni) Event Display Injected Light is uniform ( ～ 12%) Feature ・ Monitoring all channels at once with only 4 LEDs. ・ Very uniform light (No PMT saturation)

21. Gain Monitor (2) Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Relative Gain +5% -5% (Run Number) Nov.1Dec.1 Dec.24 Oct.7 Jan.16 Feb.10 14306 (99.85 %) channels are stable for 4 months. Gain drift can be corrected within 1% level precision ! Corrected ADC count

22. Muon Track Analysis (1) Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Top View Vertex As a first step, we checked and compared the basic distribution (vertex,momentum) with MC on the clean muon sample. (p μ >0.5GeV/c, ~35% eff all νint.) Timing distribution No BackGround

23. Vertex Distribution Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Data agree with MC well Z (beam) cm X Y Data MC CCQE

24. Momentum Distribution Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Data MC CCQE Good agreement  Track Length & Energy scale are OK! The threshold can be lowered

25. We installed a brand new neutrino detector “SciBar” to the K2K near detectors. - measurement of the νspectrum precisely - studying ν interactions (and more physics) SciBar is working very well from Oct. 7,2003. And observed many good neutrino events. Basic distributions reasonably agree with MC.Summary Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 More to come !

26. Supplement Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004

27. Readout Electronics VA/TA chip (Analog ASIC) –32 inputs  shaping  sample & hold  serial analog output  comparator  OR  trigger output multiplexer sample&hold slow shaper preamp. fast shaper discri. CH1 CH2 CH32 VA serial output TA (32ch OR) hold PMT signal ∝ charge 1.2  s VA/TA chip

28. S.Aoki, J.Arygyriades, S.S.Choi, M.Hasegawa, Hiraide, K.Hayashi, A.K.Ichikawa, Iinuma, Eric J., E.J.Jeon, K.K.Joo, D.Kerr, K.Kobayasi, A.Kohara, J.Kubota, M.J.Lee, I.T.Lim, H.Maesaka, O.Mineev, T.Morita, Y.Nakanishi, K.Nishikawa, K.Nitta, P.Rovegno, T.Nakaya, T.Sasaki, A.Suzuki, K.K.Shiraishi, Y.Takubo, R.Terri, M.Tuchscher, S.Yamamoto, M.Yokoyama, M.Yoshida, Z.Nawang (and more?) CNU, KEK, Hiroshima, Kobe, Kyoto, Saclay, SNU, StonyBrook, INR, Washington, Osaka, UCI (and more?) List of shift takers in this summer

29. beampedestalLEDCosmic ray 0.6s 35  s 100ns, 1take 1  s,1take Suppression mode Read out : ~100ms/event Data ADC for all channels TDC for all TA’s -> each 32channel -> 2 TDC for each PMT Suppression mode : ADC only for TA hit channel For EC, ADC for all channels, no TDC Data Taking modes

30. 4 cm 8 cm 262 cm Readout Cell Beam Fibers “spaghetti” calorimeter re-used from CHORUS 1mm diameter fibers in the grooves of lead foils 4x4cm 2 cell read out from both ends 2 planes ( 11X 0 ) Horizontal: 30 modules Vertical : 32 modules Expected resolution 14%√E Linearity: better than 10% Electron Catcher

31. SciBar Detector Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004

32. For comparing the event rate with other Detector 2627 events / 6.216x10 18 POT / 9.38t Event rate & N SK Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Efficiency ν flux Target volume No official number ( not finishing sys. error estimation & near/far calculation yet) But Consistent with other detectors

33. Fiber Attenuation Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 354.77cm ± 7.77cm Semi-Auto Attenuation Measurement System We measured all(~15,000) Fiber’s attenuation length before installation within 2% precision.  We can correct the attenuation effect ~1.4% precision.

34. Energy Calibration Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Attenuation Correction Pass Length Correction Use Cosmic Ray Muon for strip to strip relative energy scale calibration All samples can be used by correction of Attenuation and Pass length in strip (100 Hits/strip/hour  Less than 1% precision can be possible for 5days) After correction Before correction After correction Before correction

35. Timing Resolution Kyoto Univ Masaya Hasegawa Hakuba 10 th Symposium Feb. 15 – 18, 2004 Timing resolution: 1.34ns Difference of timing between two TDC channels In cosmic ray event TDC channel √2*resolution (ns) 0 2

36. dE/dx proton >  (~1GeV/c) ~ 0.1 GeV/c  ~ 1.0 GeV/c proton  dE/dx 1 cell ADC  p 0.9 GeV Pion confidence level (using only 10 hits along the track) Miss ID probability : < 20 % (1.2 GeV/c proton) < 5 % (< 1.0 GeV/c proton) With 95 % proton efficiency proton pion Particle ID (Results From Beam Test)

37. Polystylene with PPO 1% and POPOP 0.3% –Usual plastic scintillator component –Peak of emission spectrum : 420nm TiO 2 reflector (white) (0.25mm-thick) –Increase light yield –Optical isolation –Extruded together Cheep : ~$20 / kg Made by Fermilab 2.5cm 1.3cm 300cm 1.8mmφ Extruded Scintillator